I have been battling an issue in which I have been continually getting air in my fuel system. it normally takes between 25 to 45 minutes to show up. I bleed the system either while it's running or after it stalls and within a 2-15 minute time span it does it again.
I've been chasing this leak which I originally thought it was a fuel starvation or fuel contamination issue. Some of the things I have done already are as follows but not in this order:
- Changed the fuel pickup tube, tank valve, anti-siphon valve and fuel hose to primary Racor 200 series filter.
- removed and filtered (polished) all fuel at 30, 10 & 2 microns. (only about 12 gallons left of the approx 18 gallon tank). Fuel was a little dirty at the bottom of tank, that fuel was properly discarded. The only access to the tank is the through the sender unit hole.
- checked and cleared tank vent line.
- replaced the 2 micron primary filter with another 2 micron filter, then a ten micron filter.
- replaced the fuel return hose.
- replaced the fuel hose from the primary Racor filter to the lift pump.
- replaced all primary Racor seals and primer pump assembly. Also removed housing to confirm no blockages in Racor check valve, replaced ball, seal and cap.
- replaced secondary yanmar filter and bowl o-ring seal.
- replaced yanmar lift pump.
- replaced all those copper washers; before and after lift pump, before and after secondary yanmar filter housing, and at injection pump.
It's odd that it takes awhile for the problem to appear. I have never had fuel issues in the past, and never had to remove water from the oil water separated of the rancor filter. The engine is maintained regularly by me and has less than 2200 hours - 38 years old. I run the engine hard at 2,800 rpms to keep exhaust clean and avoid excessive idling. I replaced the mixing elbow (stainless) about five years ago. water flow is good, operating temperatures are normal.
I am pretty convinced it is an air issue because I can bleed it after it starts occurring and it'll be good for a few minutes and then it comes back. Other times it can run for 45 minutes under load perfectly and then all of a sudden it starts to shake and there's a loss of power to accelerate.
The only seals I have not changed is the bleeder's seal and that other screw on the top of the secondary yanmar filter housing. I will do that today as well as change the secondary filter (only because it is out) and O-ring.
I tried running fuel from a Jerry can directly to the racor filter (same issue), and directly to the lift pump but have had the same issue. I will try again directly to lift pump.
I also plan on possibly removing all the fuel and loosening the mounts to the fuel tank so I can get the last little bit out by tilting.
I use teflon tape for all the fittings on top of the tank and the rancor filter. I used all new hose clamps; the non perforated kind so they won't cut fuel lines.
When I bleed it normally only needs it prior to the injection pump or on top of the secondary filter. I haven't bled the top of the injectors - never had to do this in the past.
Any suggestions or checks would be appreciated. Needless to say it says cut into my sailing time.
Thanks for your help.
I've been chasing this leak which I originally thought it was a fuel starvation or fuel contamination issue. Some of the things I have done already are as follows but not in this order:
- Changed the fuel pickup tube, tank valve, anti-siphon valve and fuel hose to primary Racor 200 series filter.
- removed and filtered (polished) all fuel at 30, 10 & 2 microns. (only about 12 gallons left of the approx 18 gallon tank). Fuel was a little dirty at the bottom of tank, that fuel was properly discarded. The only access to the tank is the through the sender unit hole.
- checked and cleared tank vent line.
- replaced the 2 micron primary filter with another 2 micron filter, then a ten micron filter.
- replaced the fuel return hose.
- replaced the fuel hose from the primary Racor filter to the lift pump.
- replaced all primary Racor seals and primer pump assembly. Also removed housing to confirm no blockages in Racor check valve, replaced ball, seal and cap.
- replaced secondary yanmar filter and bowl o-ring seal.
- replaced yanmar lift pump.
- replaced all those copper washers; before and after lift pump, before and after secondary yanmar filter housing, and at injection pump.
It's odd that it takes awhile for the problem to appear. I have never had fuel issues in the past, and never had to remove water from the oil water separated of the rancor filter. The engine is maintained regularly by me and has less than 2200 hours - 38 years old. I run the engine hard at 2,800 rpms to keep exhaust clean and avoid excessive idling. I replaced the mixing elbow (stainless) about five years ago. water flow is good, operating temperatures are normal.
I am pretty convinced it is an air issue because I can bleed it after it starts occurring and it'll be good for a few minutes and then it comes back. Other times it can run for 45 minutes under load perfectly and then all of a sudden it starts to shake and there's a loss of power to accelerate.
The only seals I have not changed is the bleeder's seal and that other screw on the top of the secondary yanmar filter housing. I will do that today as well as change the secondary filter (only because it is out) and O-ring.
I tried running fuel from a Jerry can directly to the racor filter (same issue), and directly to the lift pump but have had the same issue. I will try again directly to lift pump.
I also plan on possibly removing all the fuel and loosening the mounts to the fuel tank so I can get the last little bit out by tilting.
I use teflon tape for all the fittings on top of the tank and the rancor filter. I used all new hose clamps; the non perforated kind so they won't cut fuel lines.
When I bleed it normally only needs it prior to the injection pump or on top of the secondary filter. I haven't bled the top of the injectors - never had to do this in the past.
Any suggestions or checks would be appreciated. Needless to say it says cut into my sailing time.
Thanks for your help.
